Debuildation is a great should-be-a-word.
You can tell who the people are that think fun is only for children because they're the ones that are relentlessly cranky and are generally unpleasant to be around ;D
Sounds like you need another shed for the Lego.
I was pretty happy with my neologism in respect of this word. I was happy and excited, or excappy as I like to say. Sometimes I say happited.
(Never said that before, just made it up.)
I need a big new shed for them! Seriously though, I'll debuilderate them and make something else from them and get double the fun...otherwise known as fouble. (Fun doubled).